On the actual post object itself, there isnt any data to be pulled out, its simply a drop down of different typed of materials.
Where i posted the example further up of the calculation i wished to try create, they would have all been repeater fields in separate posts sorted by:
Post Object | Weight | Cost
So the ideal calculation would be across posts between X and Y date range, add all rows/columns with duplicate Post Objects across all posts together. Creating a Total Weight and a Total Cost attached to that Post Type.